Tag Archives: health

Tissue sampling by piggybacking on vaccination or testing campaigns

Obtaining tissue samples from a large population of healthy individuals is useful for many research and testing applications. Establishing the distribution of genes, transcriptomes, cell distributions and morpologies in a normal population allows comparing clinical laboratory findings to reference values obtained from this baseline. The genetic composition of the population can be used to estimate historical migration patterns in paleoanthropology and selective pressures in evolutionary biology.

Gathering tissue samples from many people is expensive and time-consuming, unless it happens as a byproduct of existing programs. Collecting used vaccination needles or coronavirus nasal swabs that have a few cells attached allows anonymous tissue sampling of almost the entire population. A few cells per person are enough for many analyses in modern biology. Bulk collection of needles or swabs has built-in untraceability of biological material to an individual, which should alleviate privacy concerns and reduce the bureaucratic burden of ethics approvals.

Algae tattooed for doping and oxygen administration

The paper by Qiao et al. (2020) in Science Advances shows that unicellular algae injected near a hypoxic tumour photosynthesise oxygen in the body in response to infrared light with wavelength 660nm that penetrates >4mm into tissues. The oxygen saturation of the tumour rises from 6.2% to 30% in 2 hours after the algae receive a 5-minute laser exposure. The oxygen sensitises the tumour to radiation therapy. No side effects were found from the algae in this or previous research. The performance of the algae stayed the same when these were coated with red blood cell membranes to delay their clearance from the body.

Another application of algae that can produce oxygen in the organism is doping in sports. The algae can be tattooed under skin that is exposed to light containing enough of the wavelengths which the algae use and which can penetrate under the skin. For example, long-distance runners outdoors in warm weather have most of their skin exposed to sunlight, thus have a large surface area suitable for algal oxygen production. The additional oxygen from photosynthesis improves athletic performance. The only question is whether the oxygen generation is quantitatively fast enough to make a difference. In elite sports, every little advantage counts, so athletes are probably willing to use algae tattoos.

The algae are not dangerous even in deep blood vessels and tissues. Eventually the organism clears the algae, but the clearance of foreign particles is slower in the skin than in deep tissues, as evidenced by the persistence of ordinary tattoos. So the algae will last for a daylong competition.

Patients with breathing problems, for example with coronavirus-induced lung inflammation, may also benefit from algae tattooed on a large area of skin which is then illuminated with 660nm light. Such oxygen supplementation reduces the need for mechanical ventilation. Again, the question is the amount of oxygen from a whole-body algal tattoo.

Food refused by the most people

Which food would the greatest fraction of the world population refuse to eat? To make the question interesting, focus on widespread food items, not „interesting” local specialties like surstromming, fermented shark, maggot cheese. My guess is that pork and beef would be the most widely refused, by Muslims and Hindus respectively. Meat in general is considered objectionable by more people than vegan dishes. Refusal of plant-based food is mostly due to allergies, so soy and wheat would be the least popular. In light of this, it is interesting that the main components of the British Airways snack box on 17 May 2020 were made of wheat and pork (Jamon Iberico and a spread made of 57% bacon and 18% pork jowl). The box replaced the usual airline meal. According to British Airways, the reason was to reduce food heating on the plane during the Covid-19 pandemic. I am not sure how reducing cooking is supposed to avoid infection, but even supposing that, the pork-based snacks do not seem optimal by any criterion.

Vegan food is generally cheaper, and among animal-source foods, chicken is the cheapest, followed by turkey. So price cannot be the reason for serving pork. Airlines may try to signal wealth or that they care about passengers by offering „premium” foods, e.g. meat, and not the cheapest kind. However, this signal is undermined by the plastic boxes for the meals, the sloppy mixture of foods in the main box and the small quantities. The goal is clearly not to feed people or to keep them healthy. It does not seem reasonable for the airline to expect that it will give passengers a good taste experience.

Exercise is better than working to buy health insurance

Health insurance does not insure health, but wealth. Exercising to prevent disease is often better than working to buy health insurance to cover treating that disease. For example, cancer, stroke and cardiovascular disease predominantly occur in old age, so insurance against these is highly substitutable with exercise.

The American Association for Critical Illness Insurance in 2011 listed the following average annual premiums by age group for a male nonsmoker based on a $40,000 benefit for treatment of cancer, stroke or heart attack. Age 40: $575 to $610; age 45: $745 to $785; age 50: $940 to $980. Similar premiums in 2019 only buy cancer insurance.

At an after-tax hourly wage of $20, paying these premiums requires 30-50 work hours per year, about 0.6-1 hour per week, or 0.6-1% of waking hours. From a baseline of zero sports, one hour per week of exercise increases lifespan by one year, or by about 1/80 of life expectancy. Whether switching an hour per week from work to exercise (and cutting health insurance to compensate for the lost hourly wage) is a good investment in terms of lifespan depends on how much treatment lengthens life and how much health insurance increases the probability or quality of treatment. Data is difficult to find on both the effect of treatment on lifespan and the effect of health insurance on treatment.

The median survival rate to hospital discharge after EMS-treated out-of-hospital cardiac arrest with any first recorded rhythm is 7.9%. So for serious heart conditions, treatment and thus health insurance does not make much difference. Lung cancer treatment is said to prolong survival by about three months, which also seems small. Even if no health insurance implies no treatment, which is not the case because emergency care is still provided, investing worktime to buy health insurance seems to have a low benefit. People with cancer survive with a probability about 2/3 of the survival probability of a comparable population without cancer, so the upper bound on the benefit of treatment is 2/3 times the probability of getting cancer times the remaining life expectancy. This upper bound is loose, because zero treatment does not reduce the 5-year survival probability to zero.

Preventing overeating by advance cooking

A commitment device that prevents overeating is to only buy food that needs cooking (raw meat or fish, dry goods such as rice, flour, beans), and only buy drinks with zero calories. After each meal, measure out the ingredients for the next meal. The ingredients may be put into a pressure cooker, slow cooker, microwave or other gadget with a timer to cook, so the food is ready at the next mealtime, but not before. This procedure leaves no ready-to-eat food to snack on between mealtimes and no option to eat a larger portion than planned. The reason to portion out the next meal right after the previous meal is to do it while not hungry, thereby preventing oneself from increasing the portion size.

Sufficiently fast food delivery breaks the commitment, because it permits ordering a snack that arrives before the next mealtime. Such delivered food is typically processed and unhealthy. Vending machines, convenience stores, takeout restaurants or other sources of ready food in or near the building also weaken the commitment. Quarantine strengthens the commitment, reducing the temptation to go out seeking food.

Eating a balanced diet is more difficult when restricting food to only categories that need significant preparation time. Fruits and most vegetables can be eaten raw and juices give quick calories due to their high glycaemic index. Frozen fruits and vegetables are more difficult to snack on immediately, thus ease commitment without compromising health. Frozen fruit juice concentrate similarly delays gratification for at least a few minutes. Small berries thaw very quickly in water, so are a temptation.

Lifehacks to prevent overeating (from Youtube): eat in front of a mirror, avoid distractions like a computer, TV or smartphone while eating, use small dishes (Japanese style).

Investing time to gain lifetime

Exercising lengthens lifespan, but the return is diminishing in the amount of exercise. From zero physical activity, one extra hour of exercise per week gains about one year of life expectancy (doi:10.1371/journal.pmed.1001335.t003). Thus investing 1/168 of total weekly hours, or about 1% of the waking hours that are not spent on the quickest possible eating or hygiene, adds about 1/80 of lifespan in developed countries. This time investment has a positive return, because the percentage of lifetime spent on sports is less than the percentage gained.

Exercising may be optimal even for someone who intensely dislikes exercise, because one way to think about this investment is as choosing a year of being dead or a year of exercising plus some extra time living and not exercising. If doing sports is weakly preferred to being dead, then the first few hours of exercise per week are a positive-return investment.

One criticism of the above logic is that the lifetime gained is at the end of life, but the time doing sports is spread evenly throughout life. If extra time when old is worth much less than when young, then investing time in one’s youth to gain years of life in retirement may not be optimal. However, the question then becomes why is time less valuable when old. If the reason is lower ability to enjoy life (due to chronic diseases, cognitive decline, decreased libido, etc), then counterarguments are that exercise increases healthspan (quality-adjusted years of life) and the progress of medicine increases the quality of life in old age over time. If technological progress becomes fast enough to lengthen average lifespan by more than one year each year, then life expectancy becomes infinite. Increasing one’s lifespan to survive until that time then has an infinite return.

If life expectancy does not become infinite in the 21st century, then the diminishing return to exercise in terms of lifespan implies that there is a finite optimal amount of exercise per week, unless one’s utility increases in exercise no matter what fraction of time is spent on it. At 10 hours of physical activity per week, one needs to add about 10 more hours to gain one year of life (doi:10.1371/journal.pmed.1001335.t003). Spending 10% more of one’s waking time to gain 1/80 of lifetime is a negative-return investment in pure time terms, but may still be rational for the increase in health and quality of life.

In the research, exercise is defined as moderate- or vigorous-intensity activities: those with an intensity level of at least three metabolic equivalents (METs) according to the Compendium of Physical Activities. In other words, the energy cost of a given activity divided by the resting energy expenditure should be at least three (the approximate intensity of a brisk walk). The relevant weekly hours of moderate- or vigorous-intensity activity and the years of life gained are in the table below.

Physical Activity Level:0 0.1–3.74 3.75–7.4 7.5–14.9 15.0–22.4 22.5+

Years of life gained: 0 1.8 2.5 3.4 4.2 4.5

More efficient use of rooms and equipment during the shutdown

Instead of the labs, gyms and other rooms standing empty during the shutdown, the same isolation of people could be achieved by allocating each building or other resource to one person. Equipment from gyms or labs could be lent out for the duration of the shutdown, of course keeping a database of who borrowed what and making the borrower liable for its safe return. If only one person uses each object or building the whole time, then there is no cross-contamination or infection-spreading.

Excess demand could be rationed by lottery. Only the winner of the lottery for a resource would be allowed to use the resource, with large penalties for sharing. This would improve efficiency slightly, because one person instead of zero would be using each resource.

If the heat, water and electricity were turned off during the shutdown, then it might be more efficient to let the buildings stand empty, instead of having the utilities on and one person in each building or room. However, the lights in MIT buildings are still on at night, just like before the shutdown (and it seemed wasteful back then already).

Oxygenating blood directly

Engineering and biological constraints may make the following idea infeasible, but theoretically, one way to keep people with lung damage alive is to pump their blood through a machine that oxygenates it. Dialysis is an analogous treatment for kidney failure.

Blood would be taken out via a cannula, pumped through a system with a large surface area covered with an oxygen-permeable membrane. On the other side of the membrane is gaseous oxygen. After passing through, blood is pumped back into the body via another cannula.

The large surface area could be just two flat plates with a narrow gap between them. The oxygen-permeable plate probably needs to be thin, which makes it weak. Positioning the plates horizontally allows the pressure of the blood between the plates to support the top plate. The pressure of the oxygen above it could be regulated so the plate does not bulge outward. With careful pressure management, the plate does not have to be rigid, could be just a thin film.

The potential complications are in the details: ideally the blood would be taken from the arteries leading from the heart to the lungs and inserted into the veins going from the lungs to the heart, but puncturing these vessels is dangerous. Taking the blood from an arm or leg vein is straightforward, but there may be biological problems if oxygenated blood is pumped back into a vein instead of an artery.

Sudden lung failure does not leave enough time for such a system to be set up, because death occurs quickly without oxygen. However, if the lung failure is predicted with high probability in advance (such as when a disease is disabling the lungs), then the person can be connected to the oxygenation system and kept alive. This buys time for either the disease to be cured, in which case the lungs may become functional again, or for lung transplantation if feasible.

On the optimality of self-quarantine

Is self-quarantine early in an epidemic optimal, either individually or for society?

Individual incentives are easier to analyse, so let’s start with these. Conditional on catching a disease, other things equal, later is better. The reasons are discounting and the advances in treatment. A delay of many years may increase the severity conditional on infection (old age weakens immunity), but such long time intervals are typically not relevant in an epidemic.

Conditional on falling ill within the next year (during which discounting and advances in treatment are negligible), it is better to catch the disease when few others are infected, so hospitals have spare capacity. This suggests either significantly before or long after the peak of the epidemic. Self-quarantine, if tight enough, may postpone one’s infection past the peak.

Another individually optimal choice is to get infected early (also called vaccination with live unattenuated virus), although not if immunity increases very little or even decreases. The latter means that one infection raises the probability of another with the same disease, like for malaria, HIV and herpes, which hide out in the organism and recur. Cancer displays similar comebacks. For viral respiratory diseases, as far as I know, immunity increases after infection, but not to 100%. The optimality of self-quarantine vs trying to be infected early then depends on the degree of immunity generated, the quality of the quarantine, whether the disease will be eradicated soon after the epidemic, and other details of the situation.

Individual optimality also depends on what the rest of the population is doing. If their self-quarantine is close to perfect, then an individual’s risk of catching the disease is very low, so no reason to suffer the disutility of isolation. If others quarantine themselves moderately, so the disease will be eradicated soon, but currently is quite infectious, then self-isolation is individually optimal. If others do almost nothing, and the disease spreads easily and does not generate much immunity, then an individual will either have to self-quarantine indefinitely or will catch it. Seasonal flu and the common cold (various rhinoviruses and adenoviruses) are reasonable examples. For these, self-quarantine is individually suboptimal.

Social welfare considerations seem to weigh in favour of self-quarantine, because a sick person infects others, which speeds up the epidemic. One exception to the optimality of self-quarantine comes from economies of scale in treatment when prevalence is not so high as to overwhelm the health system. If the epidemic is fading, but the disease increases immunity and is likely to become endemic, with low prevalence, then it may be better from a social standpoint to catch the disease when treatment is widely available, medical personnel have just had plenty of experience with this illness, and not many other people remain susceptible. This is rare.

Herd immunity is another reason why self-quarantine is socially suboptimal for some diseases. The logic is the same as for vaccination. If catching chickenpox as a child is a mild problem and prevents contracting and spreading it at an older age when it is more severe, then sending children to a school with a chickenpox epidemic is a smart idea.

Reducing the duration of quarantine for vulnerable populations is another reason why being infected sooner rather than later may be socially optimal. Suppose a disease is dangerous for some groups, but mild or even undetectable for most of the population, spreads widely and makes people resistant enough that herd immunity leads to eradication. During the epidemic, the vulnerable have to be isolated, which is unpleasant for them. The faster the non-vulnerable people get their herd immunity and eradicate the infection, the shorter the quarantine required for the vulnerable.

For most epidemics, but not all, self-quarantine is probably socially optimal.

Visually distinct social classes in agrarian societies

One argument advanced for why slavery in the US was special among the world’s slaveholding societies is that one race enslaved another. However, before the age of genetic testing, the races could only have been distinguished visually. Similarly obvious differences in the looks of slaves and masters, or serfs and nobility occurred in all agrarian societies. The obviousness of distinct looks is meant in the statistical sense: with what accuracy could people classify others into slaves and masters, or peasants and lords, averaged both across the population judging and the population judged? I believe the accuracy was close to perfect – comparable to the classification accuracy of US slaves and slaveholders – for the following reasons.

Serfs were malnourished in childhood, thus short. They did hard physical labour without stretching much, thus were bent over, with back and leg muscles better developed than the rest. They spent the day outdoors without sunscreen, wearing limited clothing, thus were tanned. The lack of sunglasses caused them to squint, creating characteristic wrinkles on the face. They seldom had opportunity to wash, thus had ingrained dirt in their skin that would not have come out with a single hard scrubbing. Both corporal punishment and intrafamily violence caused many of them to have visible scars, missing teeth, crooked noses. By contrast, the well-fed nobility were tall and practised proper erect posture in childhood for table manners and dance lessons. Their physical exercise was mostly cardiovascular, without heavy lifting, thus they were either slim or fat, but not muscular. Fencing may have developed noblemen’s quadriceps, biceps and wrist muscles, not so much the trunk. The nobility’s fashionable paleness was further ensured by wearing gloves and hats and carrying parasols during the short time spent outdoors.

All these physical contrasts ensured that even in the same clothes and surroundings, without talking or moving, a peasant and a noble could be distinguished at a glance. In this sense there was nothing special about US slavery.

The belief that US slaves were more distinguishable from their owners than those of other slaveholding societies is based on modern experience – nowadays, people of the same race but different social class are difficult to distinguish based on their physical appearance. Similar nutrition, sports opportunities and outdoor exposure lead to similar stature, musculature and tan.